I have an echo 490 chainsaw and I’m having trouble with it. It’s spitting gas from the carburetor. I tried taking off the carburetor and tired cleaning it but it still ends up spitting gas then dies out. I took off the exhaust to check for scoring and so far so good. I don’t own a compression test tool but I’m thinking of reining one. Anything helps.
Need help
- Thread starter G_98
- Start date
Spitting gas where? Out the throat of the carb, past the choke butterfly and into the air box when the filter is removed?
The saw starts and idles normally?
Dies when throttle is applied?
Starts briefly and dies fairly quickly?
The saw starts and idles normally?
Dies when throttle is applied?
Starts briefly and dies fairly quickly?
So it spits out the choke I had to take off the filter, I can get it to idle fine but when I hit the throttle it it will rev up a bit then spit the gas out the choke and stall out. I tried to tune the carburetor but I just can’t make it work.
Okay, sounds a wee bit like it might be flooding rather than starving for fuel and there may be something wrong with the carb internals- I do not have the E fuel problems where I live and not the best to guess at what happens to the internals of carbs from running it.
But as a rule Echo's are lean out of the box and often this causes problems down the track with scored pistons and cylinders.
Could be compression is not allowing the right things to happen, but to buy a tester for one saw is a bit over the top as a cheap Amazon automotive tester is NOT the correct tool for the job and will most likely not give a true reading. Pull the muffler and look through the exhaust port at the piston.
Could be crud in the main jet needle seat holding the needle valve up and allowing too much fuel through, could be air leak- will idle but not sustain higher RPM, could be crap in the carb, could be damaged carb components.
If any obvious air leaks check out- I would be stripping the carb, cleaning it and fitting a new carb kit to see if anything improved.
Ok I’ll recheck everything again and see where that leads to. So I was thinking of renting a compression test tool from O’Reillys would that work or different kinds of tool?
For saws you need a compression tester designed for small volume engines- they have a different less resistant valve in the stem from normal automotive ones.
You happen to have a link?
Nope- I do not live in the States or have much of an idea of what is available over there.
But the Echo tester is designed for small engines if you can find someone willing to sell you one.
I have heard of a specific tube for the Snapon gauge with the white collar valve installed at the cylinder end of the tube that works for small engines.
I think an actual compression reading is a few steps above where you need to be- simply pull the muffler and check the piston for scoring is the first step. Echos are known to let fines past the air filter- thats your second step. Service clean and kit the carb 3rd step. Check all possible leak sites for air leaks your fourth.
You mention trying to tune the problem away- resetting the carb screws to a "base" setting would also be a good idea- try 1 to 1 1/4 turns out from lightly seated fully in.
I tried 1 1/2 turn on the L needle and 3 on the H it’s start idles but still floods it’s self with gas. It will pick up all the way to the hi rpm if I don’t slam on the throttle.
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Stump Shot
Active member
Take the "H" screw down to 1 1/2 turns as well and try again.